The present invention constitutes improvements in the rotary seal disclosed in my U.S. Pat. No.3,536,333, granted Oct. 27, 1970. In that patent I disclosed a fixed casing of cup-like construction including an inner shell portion which is replaced in the present concept by an extension of the seal ring along the shaft. This extension serves the same purpose as the inner shell which it replaces but with advantages not inherent in the prior seal.
In another aspect the foregoing construction permits the use of a secondary seal in the form of a diaphragm as well as an "O-ring" seal.
Another object is to provide a rotary seal which is more heat-resistant than that disclosed in my said patent by virtue of the use of a seal ring of thermosetting plastics composition, capable of withstanding the heat generated by the rubbing contact of the seal ring on the housing.
Another advantage of the present invention consists in utilizing a seal ring sleeve of a material which is basically a bearing material, so that, in the event of bearing failure the seal can serve as an emergency bearing.
Another advantage of my improved seal resides in the adaptability to a situation where electrolytic action can occur. This behaviour can erode the inner shell of the metal seals commonly used, e.g., in swimming pool installations. Since, with the present seal, electrically non-conducting material is used, the problem is effectively solved.